Subject: [PATCH 13/14] arm/arm64: KVM: enable kernel side of GICv3 emulation

From: [email-masked] (Andre Przywara)
Date: Fri, 20 Jun 2014 09:46:12 +0100

On 19/06/14 22:43, Chalamarla, Tirumalesh wrote:
>
>
> -----Original Message-----
> From: kvmarm-bounces at lists.cs.columbia.edu [mailto:kvmarm-bounces at lists.cs.columbia.edu] On Behalf Of Andre Przywara
> Sent: Thursday, June 19, 2014 2:46 AM
> To: linux-arm-kernel at lists.infradead.org; kvmarm at lists.cs.columbia.edu; kvm at vger.kernel.org
> Cc: christoffer.dall at linaro.org
> Subject: [PATCH 13/14] arm/arm64: KVM: enable kernel side of GICv3 emulation
>
> With all the necessary GICv3 emulation code in place, we can now connect the code to the GICv3 backend in the kernel.
> The LR register handling is different depending on the emulated GIC model, so provide different implementations for each.
> Also allow non-v2-compatible GICv3 implementations (which don't provide MMIO regions for the virtual CPU interface in the DT), but restrict those hosts to use GICv3 guests only.
>
> Signed-off-by: Andre Przywara <[email-masked]>
> ---
>  virt/kvm/arm/vgic-v3.c |  138 ++++++++++++++++++++++++++++++++++++++----------
>  virt/kvm/arm/vgic.c    |    2 +
>  2 files changed, 112 insertions(+), 28 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c index 7d9c85e..d26d12f 100644
> --- a/virt/kvm/arm/vgic-v3.c
> +++ b/virt/kvm/arm/vgic-v3.c
> @@ -34,6 +34,7 @@
>  #define GICH_LR_VIRTUALID            (0x3ffUL << 0)
>  #define GICH_LR_PHYSID_CPUID_SHIFT   (10)
>  #define GICH_LR_PHYSID_CPUID         (7UL << GICH_LR_PHYSID_CPUID_SHIFT)
> +#define ICH_LR_VIRTUALID_MASK                (BIT_ULL(32) - 1)
>
>  /*
>   * LRs are stored in reverse order in memory. make sure we index them @@ -43,7 +44,35 @@
>
>  static u32 ich_vtr_el2;
>
> -static struct vgic_lr vgic_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
> +static u64 sync_lr_val(u8 state)
> +{
> +     u64 lr_val = 0;
> +
> +     if (state & LR_STATE_PENDING)
> +             lr_val |= ICH_LR_PENDING_BIT;
> +     if (state & LR_STATE_ACTIVE)
> +             lr_val |= ICH_LR_ACTIVE_BIT;
> +     if (state & LR_EOI_INT)
> +             lr_val |= ICH_LR_EOI;
> +
> +     return lr_val;
> +}
> +
> +static u8 sync_lr_state(u64 lr_val)
> +{
> +     u8 state = 0;
> +
> +     if (lr_val & ICH_LR_PENDING_BIT)
> +             state |= LR_STATE_PENDING;
> +     if (lr_val & ICH_LR_ACTIVE_BIT)
> +             state |= LR_STATE_ACTIVE;
> +     if (lr_val & ICH_LR_EOI)
> +             state |= LR_EOI_INT;
> +
> +     return state;
> +}
> +
> +static struct vgic_lr vgic_v2_on_v3_get_lr(const struct kvm_vcpu *vcpu,
> +int lr)
>  {
>       struct vgic_lr lr_desc;
>       u64 val = vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)];
> @@ -53,30 +82,53 @@ static struct vgic_lr vgic_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
>               lr_desc.source  = (val >> GICH_LR_PHYSID_CPUID_SHIFT) & 0x7;
>       else
>               lr_desc.source = 0;
> -     lr_desc.state   = 0;
> +     lr_desc.state   = sync_lr_state(val);
>
> -     if (val & ICH_LR_PENDING_BIT)
> -             lr_desc.state |= LR_STATE_PENDING;
> -     if (val & ICH_LR_ACTIVE_BIT)
> -             lr_desc.state |= LR_STATE_ACTIVE;
> -     if (val & ICH_LR_EOI)
> -             lr_desc.state |= LR_EOI_INT;
> +     return lr_desc;
> +}
> +
> +static struct vgic_lr vgic_v3_on_v3_get_lr(const struct kvm_vcpu *vcpu,
> +int lr) {
> +     struct vgic_lr lr_desc;
> +     u64 val = vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)];
> +
> +     lr_desc.irq     = val & ICH_LR_VIRTUALID_MASK;
> +     lr_desc.source  = 0;
> +     lr_desc.state   = sync_lr_state(val);
>
>       return lr_desc;
>  }
>
> -static void vgic_v3_set_lr(struct kvm_vcpu *vcpu, int lr,
> -                        struct vgic_lr lr_desc)
> +static void vgic_v3_on_v3_set_lr(struct kvm_vcpu *vcpu, int lr,
> +                              struct vgic_lr lr_desc)
>  {
> -     u64 lr_val = (((u32)lr_desc.source << GICH_LR_PHYSID_CPUID_SHIFT) |
> -                   lr_desc.irq);
> +     u64 lr_val;
>
> -     if (lr_desc.state & LR_STATE_PENDING)
> -             lr_val |= ICH_LR_PENDING_BIT;
> -     if (lr_desc.state & LR_STATE_ACTIVE)
> -             lr_val |= ICH_LR_ACTIVE_BIT;
> -     if (lr_desc.state & LR_EOI_INT)
> -             lr_val |= ICH_LR_EOI;
> +     lr_val = lr_desc.irq;
> +
> +     /*
> +      * currently all guest IRQs are Group1, as Group0 would result
> +      * in a FIQ in the guest, which it wouldn't expect.
> +      * Eventually we want to make this configurable, so we may revisit
> +      * this in the future.
> +      */
> +     lr_val |= ICH_LR_GROUP;
> +
> +     lr_val |= sync_lr_val(lr_desc.state);
> +
> +     vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)] = lr_val; }
> +
> +static void vgic_v2_on_v3_set_lr(struct kvm_vcpu *vcpu, int lr,
> +                              struct vgic_lr lr_desc)
> +{
> +     u64 lr_val;
> +
> +     lr_val = lr_desc.irq;
> +
> +     lr_val |= (u32)lr_desc.source << GICH_LR_PHYSID_CPUID_SHIFT;
> +
> +     lr_val |= sync_lr_val(lr_desc.state);
>
>       vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)] = lr_val;  } @@ -145,9 +197,8 @@ static void vgic_v3_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
>
>  static void vgic_v3_enable(struct kvm_vcpu *vcpu)  {
> -     struct vgic_v3_cpu_if *vgic_v3;
> +     struct vgic_v3_cpu_if *vgic_v3 = &vcpu->arch.vgic_cpu.vgic_v3;
>
> -     vgic_v3 = &vcpu->arch.vgic_cpu.vgic_v3;
>       /*
>        * By forcing VMCR to zero, the GIC will restore the binary
>        * points to their reset values. Anything else resets to zero @@ -155,7 +206,14 @@ static void vgic_v3_enable(struct kvm_vcpu *vcpu)
>        */
>       vgic_v3->vgic_vmcr = 0;
>
> -     vgic_v3->vgic_sre       = 0;
> +     /*
> +      * Set the SRE_EL1 value depending on the configured
> +      * emulated vGIC model.
> +      */
> +     if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
> +             vgic_v3->vgic_sre       = ICC_SRE_EL1_SRE;
> +     else
> +             vgic_v3->vgic_sre       = 0;
>
>       /* Get the show on the road... */
>       vgic_v3->vgic_hcr = ICH_HCR_EN;
> @@ -173,6 +231,15 @@ static const struct vgic_ops vgic_v3_ops = {
>       .enable                 = vgic_v3_enable,
>  };
>
> +static void init_vgic_v3_emul(struct kvm *kvm) {
> +     struct vgic_vm_ops *vm_ops = &kvm->arch.vgic.vm_ops;
> +
> +     vm_ops->get_lr = vgic_v3_on_v3_get_lr;
> +     vm_ops->set_lr = vgic_v3_on_v3_set_lr;
> +     kvm->arch.max_vcpus = KVM_MAX_VCPUS;
> +}
> +
>  static bool vgic_v3_init_emul_compat(struct kvm *kvm, int type)  {
>       struct vgic_vm_ops *vm_ops = &kvm->arch.vgic.vm_ops; @@ -184,14 +251,28 @@ static bool vgic_v3_init_emul_compat(struct kvm *kvm, int type)
>               if (nr_vcpus > 8)
>                       return false;
>
> -             vm_ops->get_lr = vgic_v3_get_lr;
> -             vm_ops->set_lr = vgic_v3_set_lr;
> +             vm_ops->get_lr = vgic_v2_on_v3_get_lr;
> +             vm_ops->set_lr = vgic_v2_on_v3_set_lr;
>               kvm->arch.max_vcpus = 8;
>               return true;
> +     case KVM_DEV_TYPE_ARM_VGIC_V3:
> +             init_vgic_v3_emul(kvm);
> +             return true;
>       }
>       return false;
>  }
>
> +static bool vgic_v3_init_emul(struct kvm *kvm, int type) {
> +     switch (type) {
> +     case KVM_DEV_TYPE_ARM_VGIC_V3:
> +             init_vgic_v3_emul(kvm);
> +             return true;
> +     }
> +
> +     return false;
> +}
> +
>  static struct vgic_params vgic_v3_params;
>
>  /**
> @@ -233,12 +314,13 @@ int vgic_v3_probe(struct device_node *vgic_node,
>
>       gicv_idx += 3; /* Also skip GICD, GICC, GICH */
>       if (of_address_to_resource(vgic_node, gicv_idx, &vcpu_res)) {
> -             kvm_err("Cannot obtain GICV region\n");
> -             ret = -ENXIO;
> -             goto out;
> +             kvm_info("GICv3: GICv2 emulation not available\n");
> +             vgic->vcpu_base = 0;
> +             vgic->init_emul = vgic_v3_init_emul;
> +     } else {
> +             vgic->vcpu_base = vcpu_res.start;
> +             vgic->init_emul = vgic_v3_init_emul_compat;
>       }
>
> Are we returning error while GICv2 emulation is request from user when it is not supported, I might have missed the code.

Yes, we do. Actually it is right here, with the different init_emul()
functions. Check their implementations above, we only allow
KVM_DEV_TYPE_ARM_VGIC_V3 for the fist case here.

Cheers,
Andre.

>
>
> -     vgic->init_emul = vgic_v3_init_emul_compat;
> -     vgic->vcpu_base = vcpu_res.start;
>       vgic->vctrl_base = NULL;
>       vgic->type = VGIC_V3;
>
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c index fa150c7..8a584e0 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -1424,6 +1424,8 @@ static bool init_emulation_ops(struct kvm *kvm, int type)
>       switch (type) {
>       case KVM_DEV_TYPE_ARM_VGIC_V2:
>               return vgic_v2_init_emulation_ops(kvm, type);
> +     case KVM_DEV_TYPE_ARM_VGIC_V3:
> +             return vgic_v3_init_emulation_ops(kvm, type);
>       }
>       return false;
>  }
> --
> 1.7.9.5
>
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